The method to be described for the determination of tryptophan is based on the reaction between xanthydrol and tryptophan in acid solution to form a highly colored, acid-stable product (1). In the presence of excess xanthydrol the formation of xanthydryltryptophan is directly related to the quantity of tryptophan in the solution. Although other indole derivatives likewise react with xanthydrol ...

THE CLASSIC ESTIMATION OF UREA IN THE BLOOD, while not technically difficult, is time consuming, and a quicker method was sought for an emergency procedure. It has been known for many years that a solution of xanthydrol with urea forms an insoluble precipitate, dixanthylurea. Also that this precipitate dissolves in 50% sulfuric acid to give an intense yellow-colored solution which obeys Beer’s ...

Acetamide has been classified as a possible human carcinogen, but uncertainties exist about its levels in foods. This report presents evidence that thermal decomposition of N-acetylated sugars and amino acids in heated gas chromatograph injectors contributes to artifactual acetamide in milk and beef. An alternative gas chromatography/mass spectrometry protocol based on derivatization of acetami...

Although many methods for the determination of urea nitrogen have been described, few have proved highly convenient for the accurate determination of small amounts of urea nitrogen without having to make use of special apparatus or techniques. Among the older methods, the Van Slyke gasometric method (1) is generally considered the most accurate, with an allowable error of 1 per cent. This metho...

UNLABELLED BACKGROUND Methylcarbamate (MC) and ethylcarbamate (EC) are toxic compounds that commonly exist in fermented food and beverages. In order to estimate the risk for their exposure, a sensitive simultaneous analytical method is required RESULTS A simultaneous determination of MC and EC was described based on derivatization with 9-xanthydrol and consecutive detection using gas chrom...